suspension

SUSPENSION IN RACE CARS

CHAPTER 1

INTRODUCTION TO SUSPENSION

When people think of automobile performance, they normally

think of horsepower, torque and zero-to-60 acceleration. But all of the

power generated by a piston engine is useless if the driver can't control the

car. That's why automobile engineers turned their attention to the

suspension system almost as soon as they had mastered the four-stroke

internal combustion engine.

Before we go deep into our topic suspension, let us first

know what do we mean by a suspension system.

Suspension is the term given to the system of springs, shock absorbers

and linkages that connects a vehicle to its wheels and allows relative

motion between the two.

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1.1 OBJECTIVES OF SUSPENSION SYSTEM:

It maximizes the friction between tyres and road surfaces to

provide steering stability and good handling.

The irregularities on roads apply forces to the wheels.

According to Newton's laws of motion, all forces have both magnitude

and direction. A bump in the road causes the wheel to move up and

down perpendicular to the road surface. The magnitude, of course,

depends on whether the wheel is striking a giant bump or a tiny speck.

Either way, the car wheel experiences a vertical acceleration as it

passes over an imperfection.

Without an intervening structure, all of wheel's vertical energy

is transferred to the frame, which moves in the same direction. In such

a situation, the wheels can lose contact with the road completely. So

suspension prevents this situation from occurring.

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Fig 1.1 Wheels under bump

It ensures smooth ride over rough roads. Its main job is to

convert kinetic energy into heat energy that is absorbed by the

shock absorbers. Suspension absorbs the energy of the vertically

accelerated wheel, allowing the frame and body to ride

undisturbed while the wheels follow bums in the road.

Fig 1.2 over all view of suspension system

1.2 TYPES OF SUSPENSION SYSTEM:

1.2.1 DEPENDENT:

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The suspension of one wheel is diretly affected by the

suspension on the opposite wheel. It provide a rigid linkage between

the two wheels of the same axle .

Eg. Solid axle- The classic driven rigid rear axle, or so-called ‘live

axle’, is supported and located by two leaf springs .This is a dependent

suspension system, as the vertical movement of one wheel influences

the other.

Fig 1.3 Solid axle

De dion- It uses universal joints at both the wheel hubs and

differential. It uses a solid tubuler beam to hold the wheels parallel

Fig 1.4 De dion

1.22 INDEPENDENT :

It allows the wheels to rise and fall without affecting the opposite

wheel. Eg. Macpherson, Double wishbone

.

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Fig 1.4 Double wishbone

Fig 1.5 MacPherson

The most commonly used suspension systems at present are-

1. MacPherson

2. Double wishbone

MACPHERSON :

It comprises of a strut-type spring and a shock absorber

combo, which pivots on a ball joint on the single lower arm. It is the

most commonly used front suspension setup, seen in 90% of the

modern road cars such as the Porsche 911, several Mercedes-Benz

models and nearly all current BMWs.

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DOUBLE WISHBONE :

It is an independent suspension design using two

wishbone-shaped arms (called a-arms in USA & wishbones in UK) to

locate the wheel. Each wishbone or arm has two mounting points to

the chassis and one joint at the knuckle.

It is generally used in high performance road cars and Formula 1 cars

Fig 1.6 Mac Pherson

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Fig 1.6 Double Wishbone

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CHAPTER 2

COMPONENTS OF SUSPENSION SYSTEM

There are basically two components in suspension system.

2.1 SPRINGS :

A spring is an elastic device that resists movement in its direction

of work. The force it exerts is proportional to the movement of one of its ends.

Or to put this into a mathematical equation: Force = movement * spring

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constant. A high value for the spring constant makes for a stiff spring, and a low

value makes for a soft spring.

TYPES OF SPRINGS:

2.1.1 LEAF SPRING:

Leaf springs are oldest springing medium . Leaf springs are still

widely used in commercial vehicles as they are cheap, easy to manufacture

and easy to replace. The leaf is connected to the chassis at both ends directly

through its eyes .

Fig 2.1

2.1.2 RUBBER SPRING:

Although rubber seems to be a perfect springing medium, and

is light and easy to package, it never became successful because of the large

motion ratios involved which needed heavily reinforced suspension components

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2.1.3 AIR SUSPENSION:

Air enclosed in a cylinder fitted with a piston can also be

used as a suspension medium. Under the static load, the air is compressed

to a predetermined pressure, and subsequent motion of the piston either

increases or decreases the pressure and consequently increases or

decreases the force acting on the piston.Air springs are fairly widely

employed on vehicles whose laden and unladen weights differ greatly, the

latest railway coaches also use air springs.The disadvantages are high

cost, complexity of compressed air ancillary system, and therefore risk of

breakdown, more maintenance than other types of springing, and freezing

of moisture in the air in cold weather, which can cause malfunction of

valves.

. Fig 2.2

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2.1.4 COIL SPRING:

. The most common variety of springs are coil springs (see

picture), these are usually placed around the damper housing to form a spring-

damper unit.

Fig 2.3 Coil Spring

For progressive springs the spring constant will increase as the spring goes

deeper into its travel, and for regressive springs it will decrease with travel.

Most coil springs are slightly progressive, because as they compress, some of

the coils start touching each other, especially near the top and the bottom, and

hence the number of active coils decreases.

Stiffer springs yield less grip, and conversely, softer springs

yield more grip. This is because springs inhibit weight transfer, both front-to-

rear and left-to-right: for the same cornering, acceleration or braking force a

stiffer spring will compress less, resulting in less chassis movement and thus

also less weight transfer, and a soft spring will compress a lot, resulting in a lot

of weight transfer.

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Fig 2.4 Progressive Springs

But, we won’t always be able to use the spring we want: on small, high

frequency bumps, stiff springs will make the car bounce, resulting in a loss of

grip. So you need softer springs, because they allow the tires to stay in contact

with the ground. On smooth tracks however, stiff springs are the way to go, they

will also help the car’s jumping ability and responsiveness.

Coil springs may be directly connected to the wheels or may be actuated with

the help of push/pull rods via bellcranks

Fig 2.5 Double wishbone with pull rod

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2.2 DAMPERS :

Damping is needed to absorb the energy associated with suspension

travel. Bumps or lateral or longitudinal acceleration can induce that suspension

travel. Without damping, the magnitude of the suspension movement would

never stop increasing, leading to a very humorous situation. In terms of energy,

damping absorbs most of the energy the car receives as it moves, unlike

springs, which store the energy, and release it again. Dampers absorb all the

excess energy, and allow the tires to stay in contact with the ground as much as

possible. This also indicates that the damping should always be matched to the

spring ratio.

Shock absorbers (dampers) perform two functions.

They absorb any larger-than-average bumps in the road so that

the upward velocity of the wheel over the bump isn't transmitted

to the car chassis.

Secondly, they keep our wheels planted on the road.

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Fig 2.6 Damper

2.3 WISHBONE ARMS:

The other component of suspension includes A-arms or wish

bone arms wich are generally used in double wishbone suspension system.

The wishbone suspension in race cars generally has unequal length suspension

arms top and bottom in which the spring- damper system recides. If we make the

upper link relatively shorter than the lower, we achieve some significant changes

in the wheel paths. Now, in vertical travel, the upper link has a shorter radius

than the lower which results in the wheel assuming a negative camber angle in

both bump and either negative or positive camber droop. The amount of camber

change is dependent upon the relative lengths of the upper and lower links-the

shorter the upper link becomes, the steeper the camber change curve. The

assumption of negative camber reduces the change in track dimension

considerably and, with care, it can become insignificant.

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When the sprung mass rolls, the wheels are still forced into

camber angles in the same direction as the chassis roll, but the positive camber

assumed by the all important laden wheel is considerably reduced.

Unfortunately, the negative camber of the unladen wheel is increased. Although

the links are parallel to each other at ride height, the fact that they are unequal in

length means that they will not remain parallel with vertical wheel movement

(they almost do in roll) so the instantaneous swing arm length varies quite a bit.

This means that, if the wheels are allowed to travel very much, the camber

curves will become very steep indeed. If great gobs of wheel travel are required-

as in off-road racing-it is necessary to make the links closer to each other in

length-try it on the model. At any rate, the roll center with unequal but parallel

links stays pretty constant in relationship to the center of mass. Therefore the

roll moment remains more or less constant, which is a good thing.

Fig 3.4 Unequal and parallel links

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CHAPTER 3

SUSPENSION PARAMETERS

3.1 CAMBER :

Camber describes the angle between the tyre’s centreline and the

vertical plane. If the wheels of the car lean inwards, the camber angle is said to

be negative, if they lean outward, the angle is said to be positive. It is usually

measured at ride height, and angles of -0.5 to -3 are the most common.

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fig 3.1 Camber

First of all, positive camber is never used, only negative. A slight

negative camber in a turn maximizes the tire contact patch due to the way the

tire deforms under lateral load. Hence, it is good to have some negative camber

to increase cornering force.

Another reason why it is helpful to align your suspension with a

slight negative camber is that camber will change with suspension travel and

body roll. Most suspension systems are designed so that camber increases with

more suspension travel. However, camber relative to the car's chassis is not the

same thing as camber relative to the ground. It is camber relative to the ground

that affects handling. Therefore, even though camber relative to the chassis is

made to increase, camber relative to the ground may actually decrease on the

outside wheels if there is substantial body roll. To counter this tendency, it is

important to use negative camber and to control body roll.

The only drawback to negative camber is increased wear on the

inside of each tire. Since the top of the wheel is leaned in, the car is riding on the

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inside of the tire while it is on straightaways. In a corner, suspension travel and

lateral forces on the tire’s rubber compound combine to straighten the tire

relative to the ground. Therefore, the car rides evenly on the tire in turns, which

improves cornering ability. However, extra time spent driving on the inside of

the tire causes that part of the tire to heat up and wear. This effect is small if you

avoid adding too much negative camber.

On most street cars, camber is not easily adjustable. However, if

you choose to purchase aftermarket camber plates, you can set camber to

improve handling. More negative camber tends to increase tire grip in corners.

Therefore, if your car experiences understeer, you can decrease front camber

(make it more negative) to improve front grip or increase rear camber (make it

more positive) to decrease rear grip. Remember not to add too much negative or

positive camber since it will decrease the life of your tires and may cause a

blowout. Even pure race cars rarely use more than about 3 degrees of camber.

3.2 CASTER :

Caster describes the angle between the steering axis (kingpin) and

the vertical plane. In case of a double wishbone-type of suspension, the axis

through the centres of the ball links serves as a 'virtual hinge pin'. If the kingpin

is leaning back, as in the picture, the caster angle is said to be positive. Negative

caster (kingpin leaning towards the front) is never used. Note that the contact

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patch between the tire and the ground is behind the intersection point of the

extension of the kingpin and the earth. This will cause the wheels to 'trail'.

Fig 3.2 Caster

Large caster settings increase the tendency of the front

wheels to center themselves. This tendency is mainly due to the camber gain that

occurs when the steering axis is tilted and the wheels are turned. Camber gain

involved with caster is not easy to visualize. Think about the extreme case where

the steering axis is tilted to the point where it is horizontal. When you turn the

steering wheel, the front wheels would stand up on their edges. If you turn left,

the left tire will stand on its outer edge, and the right tire will stand on its inner

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edge. If you turn right, the left tire will stand on its inner edge the right on its

outer edge. The same type of camber gain, only on a smaller scale, takes place

with less caster. This camber gain is exactly what you want in a corner. Read the

previous section on camber to see what it is and why it’s beneficial.

When the tires stand up on their edges, the front of the car is

actually raised up. This is why the wheels "center themselves" when you let go

of the steering wheel. The weight of the car pushes the wheels flat on the

ground, which resets the steering. This improves high-speed stability because it

keeps the steering firmly in the center position. However, it is difficult to turn a

car with a large caster setting because, while turning, you are actually lifting the

front of the car with the steering. This effect is most visible in luxury sedans,

where high-speed stability is important and sophisticated power steering makes

up for the extra steering effort. If you watch one of these cars as the wheels turn

to full lock (maximum steering angle), you will see the front end of the car rise

slightly.

Increased caster is advantageous for racing and, in some cases,

street driving. The only disadvantage is the added steering effort. While camber

gain due to caster is generally good for increasing the grip of the front tires in a

corner, too much camber gain will cause the tires to heat up, lose grip, and wear

out prematurely. Therefore, do not use more than a few degrees of caster. If your

car uses a MacPherson Strut suspension, it may be necessary to modify or install

new strut tower mounts to be able to adjust caster.

3.3 KINGPIN INCLINATION :

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The angle in front elevation between the steering axis and the

vertical is regarded as kingpin inclination . It is also known as steering axis

inclination (SAI) and can be seen in Figure .

Fig 3.3 King pin inclination

It is used to reduce the distance measured at the ground between

steering axis and tyre’s centre of pressure in order to reduce the torque about the

steering axis during forward motion. A right kingpin inclination will reduce the

steering effort and will provide the driver with a good ‘road feel”.

4.4 SCRUB RADIUS :

Scrub radius is the distance measured at the ground between

steering axis and tyre’s centre of pressure. It is considered positive when the

steering axis intersects the ground to the inside of the wheel centerline. The

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amount of scrub radius should be kept small since it can cause excessive

steering forces [5]. However, some positive scrub radius is desirable since it will

provide feedback through the steering wheel for the driver .

Scrub radius can be reduced with KPI by designing the steering

axis so that it will intersect the ground plane closer to the wheel centerline. The

drawback of excessive KPI, however, is that the outside wheel, when turned,

cambers positively thereby pulling part of the tire off of the ground

3.5 TOE :

Toe is an alignment parameter that describes how the front

wheels are oriented with respect to each other and how the rear wheels are

oriented with respect to each other. With the steering wheel centered, if the front

wheels are pointing toward each other (from a top view), they have "toe-in" or

are “toed-in”. If they are pointing away from each other, they are said to have

"toe-out" or be “toed-out”. The same definitions apply for the rear wheels. Toe

can be measured as an angle between the perfectly straight position of a wheel

and its position after toe is adjusted. Toe can also be determined by finding the

difference between the distance separating the front edges of the wheels and the

distance separating the rear edges of the wheels. More distance between the

front edges than the rear edges is toe-out. More distance between the rear edges

than the front edges is toe-in.

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. Fig 3.4 Toe

Toe is used to change the way a car behaves on corner entry. The

more toe-in you have on a pair of wheels, the harder it is to make those wheels

turn into a corner. The more toe-out you use, the easier it is to get that pair of

wheels to turn into a corner.

Why does this happen? Let's take an example where a car with

toe-in on the front wheels is about to enter a left turn. The driver begins to turn

the wheel left. Now, the left-front tire is pointing only slightly to the left while

the right-front tire is pointing much more to the left. The problem with this is

that the left-front tire needs to turn with a greater angle than the right-front tire

because the left-front tire is on the inside of the corner and, therefore, must trace

an arc with a smaller radius than the outside tire. However, with toe-in, the left-

front tire is actually trying to trace a larger radius arc than the right-front tire. It

is difficult to make the car turn because the left-front tire is fighting the right-

front. When the car is already in the turn, weight transfers to the right-front tire

and diminishes the effect of the left-front tire. Because of this weight transfer,

toe mainly affects corner entry.

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With toe-out, the inside tire in a corner turns with a greater

angle than the outside tire (as it should). This improves the grip of the front tires

on corner entry.

In addition to corner-entry handling, toe affects straight-line

stability. Toe-in improves stability while toe-out worsens stability. This can be

explained through the same reasoning as was used to describe corner-entry

handling. Toe-out encourages turn-in since the inside tire turns at a greater angle

than the outside. Hence, the car is sensitive to the slightest steering input. Toe-

out will make the car wander on the straightaways requiring corrective steering.

The car will always be turning unless the steering is perfectly centered. With

toe-in, the inside tire fights the outside since the inside is trying to trace a larger

radius arc than the outside. As a result, toe-in discourages turn-in and makes the

car less sensitive to steering input. In other words, it is more stable.

Let's consider an example of the straight-line stability concept.

Assume you have toe-out on the rear wheels. You are traveling in a straight line

when your right-rear tire hits a small bump. It gets pushed back slightly by the

impact, and it is now pointing more to the right than the left-rear tire. Therefore,

the back of the car turns to the right until the right rear suspension comes back to

its original position. The same thing can occur with the front wheels. In fact, the

effect on the front suspension is even worse because the right-front wheel

getting pushed back, for instance, will also turn the left-front wheel to the right.

Rear toe is usually only adjusted on front-wheel drive cars or

rear wheel drive cars with independent rear suspensions. I wanted to include this

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example just to show that rear toe can be adjusted just like front toe on many

cars. With a front-wheel drive car, it is sometimes helpful to add some rear toe-

out to decrease the stability of the rear tires and counter the understeer inherent

in front-wheel drive cars. For a rear-wheel drive car with independent rear

suspension, the torque produced on the rear suspension when you step on the

throttle tends to pull the rear wheels forward on the suspension pivots. This

creates toe-in. To counter this effect, you can toe-out the rear wheels so they will

become straight when you step on the throttle. I do not recommend this since

rear toe-out in a rear-wheel drive car can cause severe oversteer. Instead of using

toe-out, install aftermarket bushings and suspension links to keep the suspension

from getting pulled forward under hard acceleration.

As you may have expected, toe increases tire wear because

the tires are fighting each other and, therefore, scrubbing along the ground. Toe-

in tends to increase tire wear on the outside edges of the tires. Toe-out tends to

increase tire wear on the inside edges of the tires. Make sure that you consider

your camber setting when adding toe-out. If you are using negative camber, you

are already wearing the inside of the tires more than normal. The combination of

excessive negative camber and toe-out can quickly wear the inside of a tire and

cause it to fail.

3.6 ROLL CENTRE :

A roll centre is an imaginary point in space, look at it as the

virtual hinge your car hinges around when its chassis rolls in a corner. It's as if

the suspension components force the chassis to pivot around this point in space.

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The roll centre is also the only point in space where a force could be applied to

the chassis that wouldn’t make it roll.

Roll centre can be defined as –

the intersection point of the lines between the tire contact patch

and the instant centres of wheel travel

Fig 3.5 Roll centre

Roll centre can be identified from this 2D front view. For parallel arms situation

the roll centre is assumed to be at the ground. The main aim of the designer is to

minimize roll centre migration.

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Now that we know where the roll centre (RC) is located, let’s look at

how it influences the handling of the car. Imagine a car, driving in a circle with a

constant radius, at a constant speed. An inertial force is pulling the car away

from the centre point, but because the car is dynamically balanced, there should

be a force equal but opposite, pulling the car towards the centre point. This force

is provided by the adhesion of the tires.

If the total mass of the car is packed into one point in space, it is the CG.

If the CG is determined correctly, both conditions should be perfectly

equivalent.

The forces generated by the tires can be combined to one force, working in the

car’s roll centre.

Two equal, but opposite forces, not working in the same point

generate a torque equal to the size of the two forces multiplied by the distance

between them. So the bigger that distance, the more efficiently a given pair of

forces can generate a torque onto the chassis. That distance is called the roll

moment. Note that it is always the vertical distance between the CG and the RC,

since the forces always work horizontally. This also explains why a vehicle with

a high CG has a tendency to lean very far in a corner, and possibly tip over.

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Fig 3.6 Roll moment

3.6.1 ROLL CENTRE POSITION :

Once the basic parameters have been determined, the kinematics

of the system can be resolved.

Kinematic analysis includes instant centre analysis for both sets of

wheels relative to the chassis and also for the chassis relative to the ground as

shown in Figure. The points labeled IC are the instant centres for the wheels

relative to the chassis. The other instant centre in Figure , the roll centre, is the

point that the chassis pivots about relative to the ground. The front and rear roll

centres define an axis that the chassis will pivot around during cornering. Since

the CG is above the roll axis for most race cars, the inertia force associated with

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cornering creates a torque about the roll centre. This torque causes the chassis to

roll towards the outside of the corner. Ideally, the amount of chassis roll would

be small so that the springs and anti-roll bars used could be a lower stiffness for

added tire compliance .

However, for a small overturning moment, the CG must be close to

the roll axis. This placement would indicate that the roll center would have to be

relatively high to be near the CG.

Unfortunately, if the roll center is anywhere above or below the

ground plane, a “jacking” force will be applied to the chassis during cornering .

For example, if the roll center is above ground, this “jacking” force causes the

suspension to drop relative to the chassis. Suspension droop is usually

undesirable since, depending on the suspension design, it can cause positive

camber which can reduce the amount of tire on the ground.

Conversely, if the roll center is below the ground plane, the suspension goes

into bump, or raises relative to the chassis, when lateral forces are applied to the

tires.

Therefore, it is more desirable to have the roll center close to the

ground plane to reduce the amount of chassis vertical movement due to lateral

forces .

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Since the roll center is an instant center, it is important to

remember that the roll center will move with suspension travel. Therefore, the

design team must check the migration of the roll center to ensure that the

“jacking” forces and overturning moments follow a relatively linear path for

predictable handling . For example, if the roll center crosses the ground plane

for any reason during cornering, then the wheels will raise or drop relative to the

chassis which might cause inconsistent handling.

Fig 4.7 Roll axis

3.6.2 ROLL AXIS :

The position of the roll axis relative to the cars CG tells a lot

about the cornering power of the car; it predicts how the car will react when

taking a turn. If the roll axis is angled down towards the front, the front will roll

deeper into its suspension travel than the rear, giving the car a ’nose down’

attitude in the corner. Because the rear roll moment is small relative to the front,

the rear won’t roll very far; hence the chassis will stay close to ride height.

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With the nose of the car low and the back up high, a bigger

percentage of the cars weight will be supported by the front tires, more tire

pressure means more grip, so the car will have a lot of grip in the front, making

it oversteer. A roll axis that is angled down towards the rear will promote

understeer.

Remember that the position of the roll centres is a dynamic

condition, so the roll axis can actually tilt when the car goes through bumps or

takes a corner.

3.6.3 ANTI ROLL BARS :

By providing a link between the left and right side suspension,

an anti-roll bar (AKA sway bar) keeps the left and right side of the suspension at

nearly the same level vertically, decreasing body roll. Larger diameter sway bars

make the suspension stiffer and transfer more weight to the end of the car where

they are installed. If the car is understeering, you can increase rear sway bar

diameter or decrease front sway bar diameter to restore balance. To correct

oversteer with sway bars, it is necessary to install either a smaller rear

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Fig 3.8 Anti roll bars

bar or a larger front bar. Most sway bars have adjustable links that can be used

to effectively increase or decrease the stiffness of the sway bar without buying a

new one.

Anti-roll bars should be chosen to match your springs. If you are

planning on installing stiff springs, there is no need for a large diameter sway

bar. The combination of stiff springs and small sway bars is enough to control

body roll. Large diameter sway bars are necessary if you will be using relatively

soft springs. This is a popular configuration since the ride is not overly harsh,

but the suspension is still stiff and body roll is reduced due to the sway bars.

Soft springs with large sway bars and stiff springs with small

sway bars accomplish virtually the same goal of providing a stable suspension

and reducing excessive weight transfer. A stiff springs/small sway bars setup is

generally better than soft springs/large sway bars because stiff springs reduce

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front-to-back weight transfer. With soft springs, side-to-side weight transfer is

controlled by the sway bars, but there is a fair amount of front-to-back weight

transfer due to the soft springs. In other words, using soft springs can result in

brake dive and acceleration squat, which are detrimental to overall handling.

3.7 WHEELBASE AND TRACK WIDTH :

Wheel base is defined as the distance between the front and rear

axle centerlines. A longer wheelbase provides a greater straight line stability,

whereas a shorter wheelbase ensures better maneuverability. Longitudinal load

transfer is inversely proportional to the wheelbase.

Trackwidth is the distance between the outer edge of the two opposite

tires in the same axle. Front and rear track width are assumed, it is an important

factor that resists overturning. Lateral load transfer is inversely proportional to

trackwidth. Generally in race cars, the trackwidth of the front tires is less than

that of rear tires. This is done for aerodynamic advantage.

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Fig 3.9 Wheelbase and trackwidth

The parameters that are generally used in F1 cars are given below.

Toe (normally Toe In 3 ~ 5 mm) Camber (normally 0.5° ~ 2°) Caster (normally 2° ~ 4°) Roll center height at design load (vis-à-vis

CG) Kingpin inclination (normally 7° ~ 8°)

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CHAPTER 4

INNOVATIONS

4.1 NITROX GAS DAMPERS:

A typical shock absorber or an hydraulic damper contains oil

with two tubes sliding inside one another and also has a piston inside. It also has

a valves inside. The oil inside the damper moves along the valves as the piston

moves up and down to absorb the shocks. These dampers have a tendency for

the oil to form foam (form bubbles) under heavy use. The foaming is usually

caused by air bubbles inside oil. This is similar to shaking a can of oil. After

shaking the oil inside the can gets foamed. Similarly the same case happens to a

hydraulic damper also. This foaming temporarily reduces the damping ability of

the unit.

Nitrox suspension used in Bajaj Pulsar In order to solve this, a

secondary cylinder is connected to the shock absorber which acts as

a reservoir for the oil and pressurized gas (nitrogen). The

pressurized nitrogen gas inside the canister prevents foaming of

hydraulic oil inside the damper due to heavy usage or damping

action. Due to this, the performance of the suspension remains

constant. This nitrogen gas also helps in absorbing the road

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undulations and provides a smooth ride for both the rider and the

pillion. The new Bajaj Pulsar 200NS uses a Nitrox piggy-back type

canister gas filled

These type of dampers provide better stability and also

provides comfortable long rides to riders as the performance remains unchanged

since the foaming never occurs. Typically, nitrogen at 30 to 300 psi is used

because the oil would not combine (burn) with the nitrogen nearly as easily as it

will with the oxygen in normal air.

Fig 4.1 Nitrox gas damper

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4.2 BOSE SUSPENSION:

Bose suspension is the biggest advance in automobile suspensiosince

the introduction of an all-independent design. The Bose system uses a linear

electromagnetic motor (LEM) at each wheel in lieu of a conventional shock-

and-spring setup. Amplifiers provide electricity to the motors in such a way that

their power is regenerated with each compression of the system. The main

benefit of the motors is that they are not limited by the inertia inherent in

conventional fluid-based dampers. As a result, an LEM can extend and

compress at a much greater speed, virtually eliminating all vibrations in the

passenger cabin. The wheel's motion can be so finely controlled that the body of

the car remains level regardless of what's happening at the wheel. The LEM can

also counteract the body motion of the car while accelerating, braking and

cornering, giving the driver a greater sense of control.

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REFERENCES

1. Allan Staniforth, ‘Competition Car Suspension’ 2. Caroll Smith , ‘Tune To Win’ (1978), pg 41-593. C. Huges, ‘ Understanding Suspension’ 4. Thomas D. Gillespie, ‘Fundamentals Of Vehicle Dynamics’, pg 237-274 5. www.howstuffworks.com/car-suspension.htm

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suspension

Documents

topic suspension

suspension setup

dependent suspension

types of suspension

view of suspension system

independent suspension

used suspension systems

opposite wheel